Two variable analysis

22

Contents:

A Correlation [11.9]

B Line of best fit by eye [11.9]

C Linear regression [11.9]

Opening problem

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The relationship between theheightandweightof members of a football team is to be investigated.

The raw data for each player is given below:

Player Height Weight Player Height Weight Player Height Weight

1 203 106 7 180 78 13 178 80

2 189 93 8 186 84 14 178 77

3 193 95 9 188 93 15 186 90

4 187 86 10 181 84 16 190 86

5 186 85 11 179 86 17 189 95

6 197 92 12 191 92 18 193 89

Things to think about:

² Are the variables categorical or quantitative?

² What is the dependent variable?

² What would the scatter diagram look like? Are the points close to being linear?

² Does an increase in the independent variable generally cause an increase or a decrease in the

dependent variable?

² How can we indicate the strength of the linear connection between the variables?

² How can we find the equation of the ‘line of best fit’ and how can we use it?

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Y:\HAESE\IGCSE01\IG01_22\455IGCSE01_22.CDR Monday, 27 October 2008 2:12:58 PM PETER